1. Field of the Invention
The invention relates in general to an edge adaptive de-interlacing apparatus and associated method, and more particularly to an edge adaptive de-interlacing apparatus and method, which can accurately obtain an edge angle by detecting extreme values or complexity of a region surrounding a target pixel.
2. Description of the Related Art
Conventional TV programs are transmitted and displayed in an interlaced way. Take television as an example, and in a process of displaying a frame, it displays an odd field and an even field alternatively. The odd field is composed of odd numbers of display lines in the frame while the even field is composed of even numbers of display lines in the frame.
The refresh rate of a television is normally 30 Hz, that is, 30 frames per second are displayed. Each frame is divided into an odd field and an even field for display. Therefore, there are 60 fields in one second for display.
Owing that progressive display has a higher quality than the interlaced display, an advanced display apparatus can perform de-interlacing display, such as a high definition TV (HDTV).
If the interlaced fields are to be displayed in a de-interlacing way, the interlaced fields should be de-interlaced first and then displayed in complete frames. There are two de-interlacing method. The first method is to merge the adjacent odd field and even field into a complete frame. This kind of method easily causes a saw-tooth effect on a moving picture, thereby influencing a frame quality.
The second de-interlacing method is to interpolate the missing display lines in the odd field or even field. The above-mentioned missing display lines are generated by respectively interpolating for each target pixel by using two vertical adjacent display lines in the same field.
When interpolating a missing line in the same field, a target pixel in that display line is used as a center to find out every possible edge angle and then an edge angle is selected. Finally, a color value of the target pixel is interpolated according to the selected edge angle.
However, the quality of the frame generated by interpolating display lines is determined by whether the selected edge angle is correct. Selecting a wrong edge angle will result in interpolating incorrect color values for the target pixel and bad interpolated image quality.